The present invention is directed to a specific mutation in SCN5A which causesdrug-induced torsade de pointes or ventricular fibrillation. Persons with themutation are predisposed to developing drug-induced torsade de pointes orventricular fibrillation when administered certain drugs. This predispositioncan be diagnosed in accordance with the present invention by analyzing the DNAsequence of the SCN5A of an individual. By screening patients for themutation, drug-induced torsade de pointes or ventricular fibrillation can beavoided. Furthermore, drugs can be tested to determine whether they will causetorsade de pointes or ventricular fibrillation.
